The present invention pertains to inflatable structures and more particularly to load supporting structures where the function is to provide a measure of resiliency or a spring effect. According, the present invention can be used to advantage in the construction of air or water beds to control the shape and resiliency thereof.
Air beds and water beds have been marketed with various types of connections between the top and bottom sheets that function as the springs or ties used in conventional bedsprings or mattresses. Exemplary connections or ties between imperforate upper and lower plastic walls of prior fluid-filled beds include inflatable cylinders or beams as shown in Nail's U.S. Pat. No. 3,705,429, and zig-zag sheets as shown in Melzer's U.S. Pat. No. 2,703,770. The cylinders and beams disclosed by Nail serve as ties between the top and bottom sheets of the structure, but are molded to a generally cylindrical or rectangular shape and, as such, cannot readily assume a smoothly flattened configuration when the structure is deflated, thus hindering the collapse thereof to a neatly folded configuration having minimum volume. This problem is overcome to some extent by use of one or more ties in the form of zig-zag sheets between the upper and lower sheets as is shown by Melzer, but this increases the cost of materials, construction is more complex, and there is limited choice of the pattern of "tufting" that can be provided. In addition, the walls of the air cavities in Melzer's structure are interconnected with each other, as are the air cavities themselves, and shape and load control functions are not equivalent to those provided by use of individual, free-standing pockets located within an outer inflatable chamber. Smoothly flattened bladder configurations are known to have been used in connection with inflatable toys and the like, but they included undesirable perforated top and/or bottom walls, permitting air to freely enter the bladder from the outside of the device.